In recent years, a wireless communication technology is rapidly developed, and requirements of systems on antenna performances are higher and higher. Large capacity, multiple functions and ultra-wideband are important development directions of current wireless communication systems. However, with increase of the numbers of used antennas, overall cost and weight of the communication system are also increased therewith, and a problem about electromagnetic compatibility is also aroused. A phased-array antenna with a relative mature technology has the defects of a complex feed network, a need of increasing phase shifters as well as a high cost and a high technological difficulty caused therefrom. A reconfigurable antenna emerges under such background.
The reconfigurable antenna use a same antenna or antenna array, and a switching device is introduced to control a radiation structure of the antenna to realize conversion of working modes, such that the functions of multiple antennas are realized. Such antenna can change its critical characteristic parameters, such as working frequency, radiation direction pattern, polarization manner, radar scattering section and input impedance according to application needs and has the characteristics of no need of manual intervention and convenience in control. The reconfigurable antenna brings a revolution for the development of antenna technologies, provides important technical guarantees for improving a capacity of the wireless communication systems, expanding functions of the systems, increasing working bandwidths of the systems and realizing, software defined radio, and the like, and will bring a far-reaching influence for the wireless communication technology.
At present, there is one type of reconfigurable antenna on the market, an important constituting part thereof, i.e., a SPiN diode (also referred to as surface positive-intrinsic-negative diode) adopts a bulk silicon material, such material has the problem of lower carrier mobility of an intrinsic region, which affects a carrier concentration of the intrinsic region of the SPiN diode and further affects a concentration of solid-state plasma. Besides, a P region and an N region of such structure mostly adopt an implantation process, and such method requires large implantation dosage and energy, has high requirements on equipment and is incompatible with the existing process. However, when a diffusion process is adopted, a junction depth is deeper, but the P region and N region have relatively larger areas, resulting in a low integration level and an uneven doping concentration, thereby affecting electrical properties of the SPiN diode and leading to poor controllability in concentration and distribution of the solid-state plasma
Therefore, it is an urgent problem to select what kind of material and process to manufacture a diode string of a proper material to apply to a loop frequency-reconfigurable antenna.